The major current objectives of the Pathology Committee of the Cancer and Leukemia Group B (CALGB) include: 1) provision of quality control in the histopathologic diangosis of various noeplasms in order to insure proper patient accession into protocols, 2) correlation of histologic classes of noeplasms with the incidence and duration of remission and overall survival, 3) correlation of cytologic types of leukemias and lymphomas with immunologic, cytogeneic, and molecular biologic markers, 4) study of malignant mesotheliomas by means of morphologic, histochemical and ultrastructural methods in order to classify and distinguish these neoplasms from other cancers, 5) determination of whether the fraction of cells in the S-phase of the proliferative cycle (S%), as determined by flow cytometry or 3H-thymidine, bromodeoxyuridine (BUdR) and Ki-67 labelling indices, provide independent prognostic information in patients with breast cancer, and 6) identification of long-term survivors with small cell lung cancer by means of a monoclonal antibody reagent (SCCL 175) which was developed against small cell carcinoma cells.